Sane use of test_expect_failure

Originally, test_expect_failure was designed to be the opposite
of test_expect_success, but this was a bad decision.  Most tests
run a series of commands that leads to the single command that
needs to be tested, like this:

    test_expect_{success,failure} 'test title' '
	setup1 &&
        setup2 &&
        setup3 &&
        what is to be tested
    '

And expecting a failure exit from the whole sequence misses the
point of writing tests.  Your setup$N that are supposed to
succeed may have failed without even reaching what you are
trying to test.  The only valid use of test_expect_failure is to
check a trivial single command that is expected to fail, which
is a minority in tests of Porcelain-ish commands.

This large-ish patch rewrites all uses of test_expect_failure to
use test_expect_success and rewrites the condition of what is
tested, like this:

    test_expect_success 'test title' '
	setup1 &&
        setup2 &&
        setup3 &&
        ! this command should fail
    '

test_expect_failure is redefined to serve as a reminder that
that test *should* succeed but due to a known breakage in git it
currently does not pass.  So if git-foo command should create a
file 'bar' but you discovered a bug that it doesn't, you can
write a test like this:

    test_expect_failure 'git-foo should create bar' '
        rm -f bar &&
        git foo &&
        test -f bar
    '

This construct acts similar to test_expect_success, but instead
of reporting "ok/FAIL" like test_expect_success does, the
outcome is reported as "FIXED/still broken".

Signed-off-by: Junio C Hamano <gitster@pobox.com>

t/t5510-fetch.sh

@@ -95,7 +95,7 @@ test_expect_success 'fetch following tags' '
 
 '
 
-test_expect_failure 'fetch must not resolve short tag name' '
+test_expect_success 'fetch must not resolve short tag name' '
 
 	cd "$D" &&
 
@@ -103,11 +103,11 @@ test_expect_failure 'fetch must not resolve short tag name' '
 	cd five &&
 	git init &&
 
-	git fetch .. anno:five
+	! git fetch .. anno:five
 
 '
 
-test_expect_failure 'fetch must not resolve short remote name' '
+test_expect_success 'fetch must not resolve short remote name' '
 
 	cd "$D" &&
 	git-update-ref refs/remotes/six/HEAD HEAD
@@ -116,7 +116,7 @@ test_expect_failure 'fetch must not resolve short remote name' '
 	cd six &&
 	git init &&
 
-	git fetch .. six:six
+	! git fetch .. six:six
 
 '
 
@@ -139,10 +139,10 @@ test_expect_success 'create bundle 2' '
 	git bundle create bundle2 master~2..master
 '
 
-test_expect_failure 'unbundle 1' '
+test_expect_success 'unbundle 1' '
 	cd "$D/bundle" &&
 	git checkout -b some-branch &&
-	git fetch "$D/bundle1" master:master
+	! git fetch "$D/bundle1" master:master
 '
 
 test_expect_success 'bundle 1 has only 3 files ' '